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 * Copyright (C) Codehaus.org                                                *
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 * Licensed under the Apache License, Version 2.0 (the "License");           *
 * you may not use this file except in compliance with the License.          *
 * You may obtain a copy of the License at                                   *
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 * http://www.apache.org/licenses/LICENSE-2.0                                *
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package com.googlecode.lazyparsec;

import com.googlecode.lazyparsec.Tokens.Fragment;

/**
 * Returns the fragment text if the token is an instance of {@Link Fragment} with expected tag.
 *
 * @author Ben Yu
 */
abstract class IsFragment implements TokenMap<String> {

    public String map(final Token token) {
        final Object val = token.value();
        if (val instanceof Fragment) {
            Fragment c = (Fragment) val;
            if (!isExpectedTag(c.tag())) return null;
            return c.text();
        } else return null;
    }

    /**
     * Is {@code type} expected?
     */
    abstract boolean isExpectedTag(Object type);
}